PROJECT SUMMARY This study will focus on the ongoing disaster affecting the people of Puerto Rico in the aftermath of Hurricane Maria. The extremely slow pace of recovery and lack of alternative housing options have forced residents to continue to live in water-damaged homes affected by fungal contamination. The impact of these conditions on human health is of great concern, particularly for respiratory conditions such as asthma. To protect the health of residents in water-damaged buildings, we must understand the fungal communities that proliferate in damaged homes as well as the health concerns associated with these conditions and their relationship to the built environment. We hypothesize that long-term water damage to houses in Puerto Rico will result in flood-related indoor fungal communities that can activate inflammatory immune mechanisms associated with respiratory diseases. We propose to collect indoor and outdoor samples from 50 homes split between water-damaged and non-flooded (control) homes in San Juan, Puerto Rico. We will couple molecular and immunological analytical techniques to simultaneously identify indoor fungal microbiota associated with flood damage and airborne pro- inflammatory microbial compounds that contribute to poor respiratory health. We will also survey residents and assess conditions within the study homes to identify relationships between occupant respiratory health and home characteristics including flood damage, indoor fungi and pro-inflammatory potential of indoor dust. Our results will inform homeowners as well as stakeholders at the city, state and federal levels about the human health and infrastructure consequences associated with extensive and protracted water damage in homes following an extreme climatic event such as a hurricane. Understanding these consequences is essential for developing effective mitigation strategies to protect human health.